Automated Self-Propelled Gun (SPG) Versatility. Power. Maneuverability. Agile as an IFV, powerful as a Tank, mighty as a Howitzer, can be used as a Mortar. The 2S31 Vena 120mm Automated Self-Propelled Gun is a highly maneuverable and powerful weapon system, designed to engage various static and moving, protected and unprotected targets with direct and mortar fire. 2S31 Vena is mounted on the BMP-3 armoured tracked ...